The present invention relates to a storage apparatus that has a variable resistance element in which the resistance value of a recording layer is changed reversibly by applying potentials of different polarities to two electrodes, and which stores information using a change in resistance of the variable resistance element.
Recently, with the dramatic spread of information communication devices, portable terminal devices and the like, higher performance such as a higher degree of integration, higher speed, lower power consumption and the like is required of elements such as a memory, a logic and the like forming these devices. Of such elements, nonvolatile memories, in particular, are considered to be essential in the ubiquitous age.
Nonvolatile memories enable protection of important information including personal information even when power supply exhaustion or trouble occurs, or a server and a network are disconnected due to some problem. Recent portable terminal devices are designed to minimize power consumption by setting an unused circuit block in a standby state. However, when a nonvolatile memory that can serve as a high-speed work memory and a high-capacity storage memory can be realized, wastes of power consumptions and memory can be eliminated. Further, when a high-speed and high-capacity nonvolatile memory can be realized, a so-called “instant on” function, which enables an instant start on turning on power, can also be realized.
Various nonvolatile memories have been proposed, and some nonvolatile memories, such as flash memories, for example, are put to practical use. On the other hand, a nonvolatile memory using a variable resistance element that stores information using a change in resistance has recently been proposed as a new-generation memory device that operates on a relatively low voltage, has a high storage density, and enables high-speed random access operation (see Japanese Patent Laid-open No. 2004-87069 and Japanese Translations of PCT for Patent No. 2002-536840, for example). The variable resistance element is formed such that a resistance value in the element is reversibly changed to a high resistance value or a low resistance value by applying potentials of different polarities to the element. Specifically, there are a variable resistance element using spin injection magnetization reversal as disclosed, for example, in Japanese Patent Laid-open No. 2004-87069 and a variable resistance element using mobile ions such as Ag and the like as disclosed, for example, in Japanese Translations of PCT for Patent No. 2002-536840.